Circadian disruption may lead to bone loss in healthy men

In healthy men, 3 weeks of sleep restriction and circadian disruption may decrease bone formation without increasing bone resorption, according to findings published in The Journal of Clinical Endocrinology & Metabolism.

Christine Swanson, MD, of the division of endocrinology and bone and mineral unit at Oregon Health & Science University and the division of endocrinology at the University of Colorado, and colleagues evaluated 10 healthy men (six younger men: mean age, 23.5 years; four older men: mean age, 58.75 years) to determine the effect of sleep restriction with circadian disruption on bone biomarkers.

Circadian stability at the outset was ensured by participants reporting no regular night-shift work within 3 years and no travel across more than two time zones within 3 months. Participants were subjected to recurring 28-hour sleep-wake cycles with a 21.47-hour wake episode and a 6.53-hour sleep opportunity during a 3-week interval to experience circadian disruption.

Younger participants experienced greater declines in P1NP levels after the intervention (–28%; P < .001) compared with the older participants (–18.2%; P < .001). No change was observed in CTX after the intervention. In contrast to the older participants, the younger participants had higher sclerostin levels after the intervention (P < .001). Fibroblast growth factor-23 levels were 7.1% lower in all participants after the intervention (P < .001).

Before and after the intervention, CTX and P1NP were moderately correlated (P = .05).

“These results suggest that 3 weeks of exposure to circadian disruption with concurrent sleep restriction can lead to an uncoupling of bone turnover and a potential ‘catabolic’ or ‘bone loss window,’ wherein bone formation is decreased, but bone resorption is unchanged,” the researchers wrote. “Such changes may possibly explain the increased incidence of fractures reported in women who worked rotating night shifts. These data further suggest that circadian disruption and/or sleep restriction may be more detrimental to bone health in early adulthood (ie, bone consolidation).” – by Amber Cox